Thank you for your answer about the names of files.
I builded a personal version of MatterOverdrive.
I got the source code from github, fixed it and builded it.
It seems that 0.4.2-hotfix1 is the last version of MO because there are there years since the latest issue request on github.
At that time, the GT6 was developing so there may not have chance to find this problem.
Now MO is DEAD. I think it is hard to release a new version to fix this issue.
By the way, the color is not suitable with GT6 so why not add a texture which is owned by GT6 and force the GT6 to use it? Tn and Dn appeared in GT6’s material list.